13 resultados para Critical Film Thickness
em CentAUR: Central Archive University of Reading - UK
Resumo:
X-ray reflectivity (XR) and grazing incidence X-ray diffraction (GIXD) have been used to examine an oxyethylene-b-oxybutylene (E23B8) copolymer film at the air-water interface. The XR data were fitted using both a one- and a two-layer model that outputted the film thickness, roughness, and electron density. The best fit to the experimental data was obtained using a two-layer model (representing the oxyethylene and oxybutylene blocks, respectively), which showed a rapid thickening of the copolymer film at pressures above 7 mN/m. The large roughness values found indicate a significant degree of intermixing between the blocks and back up the GIXD data, which showed no long range lateral ordering within the layer. It was found from the electron density model results that there is a large film densification at 7 mN/m, possibly suggesting conformational changes within the film, even though no such change occurs on the pressure-area isotherm at the same surface pressure.
Resumo:
Ellipsometry and atomic force microscopy (AFM) were used to study the film thickness and the surface roughness of both 'soft' and solid thin films. 'Soft' polymer thin films of polystyrene and poly(styrene-ethylene/butylene-styrene) block copolymer were prepared by spin-coating onto planar silicon wafers. Ellipsometric parameters were fitted by the Cauchy approach using a two-layer model with planar boundaries between the layers. The smooth surfaces of the prepared polymer films were confirmed by AFM. There is good agreement between AFM and ellipsometry in the 80-130 nm thickness range. Semiconductor surfaces (Si) obtained by anisotropic chemical etching were investigated as an example of a randomly rough surface. To define roughness parameters by ellipsometry, the top rough layers were treated as thin films according to the Bruggeman effective medium approximation (BEMA). Surface roughness values measured by AFM and ellipsometry show the same tendency of increasing roughness with increased etching time, although AFM results depend on the used window size. The combined use of both methods appears to offer the most comprehensive route to quantitative surface roughness characterisation of solid films. Copyright (c) 2007 John Wiley & Sons, Ltd.
Resumo:
Epitaxial ultrathin titanium dioxide films of 0.3 to similar to 7 nm thickness on a metal single crystal substrate have been investigated by high resolution vibrational and electron spectroscopies. The data complement previous morphological data provided by scanned probe microscopy and low energy electron diffraction to provide very complete characterization of this system. The thicker films display electronic structure consistent with a stoichiometric TiO2 phase. The thinner films appear nonstoichiometric due to band bending and charge transfer from the metal substrate, while work function measurements also show a marked thickness dependence. The vibrational spectroscopy shows three clear phonon bands at 368, 438, and 829 cm(-1) (at 273 K), which confirms a rutile structure. The phonon band intensity scales linearly with film thickness and shift slightly to lower frequencies with increasing temperature, in accord with results for single crystals. (c) 2007 American Institute of Physics.
Resumo:
Ultrathin bimetallic layers create unusual magnetic and surface chemical effects through the modification of electronic structure brought on by low dimensionality, polymorphism, reduced screening, and epitaxial strain. Previous studies have related valence and core-level shifts to surface reactivity through the d-band model of Hammer and Nørskov, and in heteroepitaxial films this band position is determined by competing effects of coordination, strain, and hybridization of substrate and overlayer states. In this study we employ the epitaxially matched Pd on Re{0001} system to grow films with no lateral strain. We use a recent advancement in low-energy electron diffraction to expand the data range sufficiently for a reliable determination of the growth sequence and out-of-plane surface relaxation as a function of film thickness. The results are supported by scanning tunneling microscopy and X-ray photoemission spectroscopy, which show that the growth is layer-by-layer with significant core-level shifts due to changes in film structure, morphology, and bonding.
Resumo:
The article compares Florian Henckel von Donnersmarck's film Das Leben der Anderen (2006) with Kurt Maetzig's early post-war film Ehe im Schatten (1947). The comparison is based on significant narrative and thematic elements which the films share: They both have a ‘theatre couple’, representatives of the ‘Bildungsbürgertum’, at the centre of the story; in both cases the couple faces a crisis caused by the first and second German dictatorship respectively and then both try to solve the crisis by relying on the classical ‘bürgerliches Erbe’, particularly the ‘bürgerliches Trauerspiel’. The extensive use of the ‘bürgerliches Erbe’ in the films activates the function this heritage had for the definition of the German nation in the nineteenth century. However, while Maetzig's film shows how the ‘heritage’ and its representatives fail in the face of National Socialism, von Donnersmarck's film claims the effectiveness of this ‘heritage’ in the fight against the East German dictatorship. Von Donnersmarck thus inverts a critical film tradition of which Ehe im Schatten is an example; furthermore, as this tradition emerged from dealing with the Third Reich, von Donnersmarck's film, it will be argued, is more interested in the redemption of the Nazi past than the East German past.
Resumo:
Atomic force microscopy is used to study the ordering dynamics of symmetric diblock copolymer films. The films order to form a lamellar structure which results in a frustration when the film thickness is incommensurate with the lamellae. By probing the morphology of incommensurate films in the early ordering stages, we discover an intermediate phase of lamellae arranged perpendicular to the film surface. This morphology is accompanied by a continuous growth in amplitude of the film surface topography with a characteristic wavelength, indicative of a spinodal process. Using selfconsistent field theory, we show that the observation of perpendicular lamellae suggests an intermediate state with parallel lamellae at the substrate and perpendicular lamellae at the free surface. The calculations confirm that the intermediate state is unstable to thickness fluctuations, thereby driving the spinodal growth of surface structures.
Resumo:
The oxidation of organic films on cloud condensation nuclei has the potential to affect climate and precipitation events. In this work we present a study of the oxidation of a monolayer of deuterated oleic acid (cis-9-octadecenoic acid) at the air-water interface by ozone to determine if oxidation removes the organic film or replaces it with a product film. A range of different aqueous sub-phases were studied. The surface excess of deuterated material was followed by neutron reflection whilst the surface pressure was followed using a Wilhelmy plate. The neutron reflection data reveal that approximately half the organic material remains at the air-water interface following the oxidation of oleic acid by ozone, thus cleavage of the double bond by ozone creates one surface active species and one species that partitions to the bulk (or gas) phase. The most probable products, produced with a yield of similar to(87 +/- 14)%, are nonanoic acid, which remains at the interface, and azelaic acid (nonanedioic acid), which dissolves into the bulk solution. We also report a surface bimolecular rate constant for the reaction between ozone and oleic acid of (7.3 +/- 0.9) x 10(-11) cm(2) molecule s(-1). The rate constant and product yield are not affected by the solution sub-phase. An uptake coefficient of ozone on the oleic acid monolayer of similar to 4 x 10(-6) is estimated from our results. A simple Kohler analysis demonstrates that the oxidation of oleic acid by ozone on an atmospheric aerosol will lower the critical supersaturation needed for cloud droplet formation. We calculate an atmospheric chemical lifetime of oleic acid of 1.3 hours, significantly longer than laboratory studies on pure oleic acid particles suggest, but more consistent with field studies reporting oleic acid present in aged atmospheric aerosol.
Resumo:
A Theatre to Address explores the work of contemporary artists who use text as both a visual and sonic form. In this programme, text appears not primarily as a means of communication, but as something which has shape and structure of its own. The Reading Room will also be displaying work that looks at text as concrete or visual poetry, and the script in artists' practice. Clare Gasson presents a new work The traveller - walking walking walking through ... that explores the connection between the text, the rhythm and the action. Maryam Jafri presents a performance-lecture Death With Friends, a body of visual and textual material that forms the basis for her new film of the same name. Pil and Galia Kollectiv present a radical worship for the apocalypse, featuring a sermon for the Church of the Atom with live music by Gelbart.
Resumo:
This article extends the traditions of style-based criticism through an encounter with the insights that can be gained from engaging with filmmakers at work. By bringing into relationship two things normally thought of as separate: production history and disinterested critical analysis, the discussion aims to extend the subjects which criticism can appreciate as well as providing some insights on the creative process. Drawing on close analysis, on observations made during fieldwork and on access to earlier cuts of the film, this article looks at a range of interrelated decision-making anchored by the reading of a particular sequence. The article examines changes the film underwent in the different stages of production, and some of the inventions deployed to ensure key themes and ideas remained in play, as other elements changed. It draws conclusions which reveal perspectives on the filmmaking process, on collaboration, and on the creative response to material realities. The article reveals elements of the complexity of the process of the construction of image and soundtrack, and extends the range of filmmakers’ choices which are part of a critical dialogue. Has a relationship to ‘Sleeping with half open eyes: dreams and realities in The Cry of the Owl’, Movie: A Journal of Film Criticism, 1, (2010) which provides a broader interpretative context for the enquiry.
Resumo:
In order to consider our emotional and physical involvement with film this chapter explores the rapport between camera and performer and how this impacts on the construction of engagement, drawing on critical approaches across the disciplines of film, dance and philosophy to describe our spatial, emotional and sensuous relationship to characters and bodies on-screen. Concern with the relationship between what is happening on screen and the shaping of our engagement is developed through attention to the effort of a particular performance, using close analysis to make sense of the affect invited by qualities of movement and how they are presented in moment from Rosemary’s Baby (Polanski, 1968).
Resumo:
This chapter focuses on critical responses to Alfred Hitchcock’s Rear Window, especially their construction of disability. The suggestion is that such criticism takes the disabled body to be both necessary and superfluous to the meaning of the film, a difficulty that, I argue, can be read more widely within film theory. Ever since Christian Metz’s ‘the Imaginary Signifier’, the condition of being ‘bound to a wheelchair’ is understood to have a resonance for theories of film spectatorship, but only ever in a sense that does away with the wheelchair as a mark of difference.